Principle of Operation
The Ploughshare® Shovels are specially arranged and rotate on a horizontal shaft in a horizontal, cylindrical mixing drum. The size, number and positioning, geometric shape and peripheral speed of the mixing elements are designed to cause three dimensional movement of the components of mix. Complete fluidization and turbulence of the mixed materials is created which eliminates dead spaces or low movement zones in the mixing drum; thus promoting high speed, precise mixing.
The specially shaped shovels lift the product radially from the wall of the drum to prevent particles from becoming compressed between the mixing elements and the drum wall. The mechanically generated fluid bed is therefore ideal for gentle mixing if fragile and heat sensitive components are included in the mix.
Optional Modified Designs
Modified Ploughshare Shovels – Becker Shovels – can be used for special applications or particular component characteristics to further intensify this effect. In many cases, in particular in combined processes, the effect of the Ploughshare® mixing elements may require additional shear and this is provided by separately driven, high speed choppers.
To enhance short mixing times and to minimize the drive power consumption. The low-maintenance concept of Lödige Mixers guarantees maximum availability of production units.
The excellent accessibility to all inside parts of the mixer considerably reduces the time and expense for cleaning and inspection. The mixers can be adapted as an option to WIP processes and therefore provide the highest standard of hygiene for even the most difficult, microbiological components.
Lodige Process Technology offers a large variety of mixing systems for industrial applications, both horizontal mixers and vertical systems are available. With Ploughshare® mixing technology the mixing shaft and the tools are horizontally installed, thus achieving, at corresponding movement, a product reaching from a loose product bed up to a mechanically generated fluidized bed. The installation of fast-rotating choppers enables the mixing of products tending to lump formation as the mixing tools push the material directly into the chopper field. Since the mix action is so efficient, liquids can be added and incorporated into the mix quite easily as shown from the below diagram. In fact, there are other liquid add techniques developed but not shown.
The Lödige dryer was developed from the Lödige Ploughshare® Mixer. It consists of horizontal, cylindrical drum with heating jacket. The product is heated by the jacket and the product moisture is thereby evaporated. A horizontal shaft along the longitudinal axis of the dryer drum is equipped with shovels for mixing the drying product according to the fluid bed principle. This ensures that the product is heated evenly (no local hot spots) and moist material is brought continuously in contact with the heated wall. The intensity of the product movement increases during the drying process while moisture and therefore viscosity decrease. Use of choppers at the right time produces a bigger heat transfer area and therefore leads to increased drying speed. The dryer is heated by the jacket operated with hot water, steam or thermal oil. Molten salt or an electric heating can also be used to achieve higher temperatures.
4 Types of Ploughshare Drying
Lodige Process Technology reactors operate in the same way as Lodige Ploughshare® mixers. Ploughshare® shovels rotate on a horizontal shaft in a cylindrical drum creating in a mechanically generated fluid bed. This results in very intensive interaction of the reactants and intensive contact with the jacketed drum surface.
The aim of a chemical reaction is to obtain a 100% transformation of the reaction agents and this practically occurs automatically if the reaction agents have a high chemical affinity for each other. However, other reactions may require specific operating or reaction conditions such as temperature and pressure. Tests in Lödige DRUVATHERM® reactors compared to classical autoclaves clearly prove that reactors are more effective due to defined, homogeneous mixing of the product and Reactions in a DRUVATHERM® DVT are carried out more rapidly, ensure gentle treatment of the product and provide higher yield. The transformation is therefore more successful and creates less undesirable by-products, which means that the process is more effective and the end product of higher purity.
Lodige Process Technology mixing systems are utilized in granulation, agglomeration and coating applications for various industries.
The mixing tools are generating a mechanical fluid bed and a liquid serving as a binding agent is added to the primary particles in the fluid bed. The liquid is homogeneously distributed in the material and in some cases, the mixing process may be supplemented by the high speed chopper assemblies which impart more shear. The intensive mixing process makes for countless contact of the primary particles among each other. The binding force will thus become greater, and the primary particles will be combined to granulates/agglomerates. The final size and the grain size distribution can be influenced by the binding agent quantity, residence time, speed and other machine parameters.
In the case of coating of particles, the liquid is simply dispersed or distributed over the mechanically fluidized bed which individualizes each particle, allowing for effect coating or surface treatment of each. Subsequent drying of the coated material can be accomplished in the same vessel.